Sexy Shrimp (Thor amboinensis)
The Sexy Shrimp (Thor amboinensis), known to tropical fish keeping enthusiasts as the High-backed Shrimp, Squat Shrimp, or Dancing Shrimp, is a marine decapod crustacean species that is found globally throughout the tropical waters of the Indo-West Pacific and the western Atlantic Ocean.
Sexy Shrimp are normally found among the coral reefs and shallow lagoons of their range at depths from the low intertidal zone to around 60 feet, where they often set up a commensal relationship with various species of large sea anemones and corals.
Thor amboinensis are not natural diggers. They are very active and constantly on the move throughou the day and night, and are most frequently seen actively displaying on or near their host invertebrates.
Substantial numbers of Sexy Shrimp can typically be found clustered closely together around the base or the
Sexy Shrimp (Thor amboinensis)
tentacles of host anemones, carpet anemones, or large polyp stony (LPS) corals. Apparently, the stinging tentacles of these hosts provide the tiny Sexy Shrimp a safe haven from benthic and pelagic predators that would otherwise easily snap them up from below or above.
Although Sexy Shrimp are frequently found together in large numbers around a single host, they are not necessarily social animals in a complex structural school. They are a docile, completely non-aggressive species that readily associate with conspecifics, forming peaceful colonies that safely share the exact same host territory without any infighting.
Thor amboinensis are exceptionally tiny marine crustaceans that seldom exceed 0.5 to 0.75 inches in body length.
Sexy Shrimp (Thor amboinensis)
True Sexy Shrimp have a striking, highly distinct coloration featuring a bright orange-brown to olive body adorned with large, iridescent white or silver spots outlined in fine blue rings. They possess a characteristic behavior where they continuously arch their abdomens upward over their heads and wag their tails back and forth in a distinct “dancing” motion, which gives them their unique common name.
Sexy shrimp are protandric hermaphrodites, meaning they function initially as males and later transition into larger females as they mature. Unlike many smaller shrimp species, they do display mild external sexual dimorphism; mature females are significantly larger than males and possess slightly different abdominal plating to support egg carrying.
Unlike larger marine organisms that can rely on size or a heavy shell, the Sexy Shrimp does not have a proper individual defensive mechanism. Instead, they rely almost entirely on their tiny size, transparent camouflage elements, and the chemical protection of their stinging host anemone. Their top speed is quite quick when they utilize a rapid backward tail-flick to jump through the water column directly into the protective folds of their host when threatened.
The Sexy Shrimp is completely reef safe with caution and is best housed in a well-established 5 or 10 gallon nano or pico reef aquarium with a fine coralline gravel or sandy substrate, plenty of live rock arranged into mini hiding places, and a suitable host coral or anemone for them to inhabit. Although a large colony of Sexy Shrimp may occasionally nip slightly at the mucus layer of a host coral if alternative food sources are scarce, they are far too small to cause any serious damage to any decor in a reef aquarium.
Sexy Shrimp are non-aggressive and exceptionally docile by nature. They are at their best in a small, dedicated nano tank with peaceful, tiny tank mates like Neon Gobies, Clown Gobies, or small, non-carnivorous fish.
Good tankmates include Bumble Bee Snails, Cerith Snails, Trochus Snails, and other miniature ornamental shrimp like Pederson Cleaner Shrimps.
Because their minuscule size makes them an instant snack for almost any predatory tank mate, avoid housing them with Coral Banded Shrimp, Hawkfish, Dottybacks, most species of crab, any large or aggressive fish, and all carnivorous species.
Like other nano cleanup crew members, the Sexy Shrimp (Thor amboinensis) has an opportunistic appetite for debris, which makes them great candidates for a micro tank clean-up crew. In the aquarium, they are excellent miniature scavengers that thrive on organic debris, sloughed tissue, microscopic detritus, and mucus shed by their host anemones or corals.
Provided they are housed in small aquariums without predatory fish, Sexy Shrimp are relatively easy to keep. They
Sexy Shrimp (Thor amboinensis)
are very sensitive to sudden changes in water values, especially parameters like salinity, pH, and water temperature. In addition to stable water quality, they require a constant food source, a stable tropical water temperature between 72–78°F, and adequate iodine levels to support their frequent molting process.
An excellent filtration system and regular partial water changes are highly recommended to keep this tiny species healthy.
Despite a handful of reports of successful captive breeding; Sexy Shrimp do not generally yield surviving offspring in a standard community aquarium environment.
Breeding pairs form naturally within a colony, and mating occurs right after the female molts. The female carries a small cluster of bright fertilized eggs under her abdomen for roughly 2 to 3 weeks. The tiny larvae are released into the water column after dark. In a standard nano or small reef aquarium, the release may briefly trigger a feeding response from corals. The microscopic free-swimming larvae are usually regarded as planktonic food and are quickly consumed before they can ever complete their complex larval molting stages.
In their natural environment, the Sexy Shrimp feeds on microscopic detrital elements, organic film, mucus from their host coelenterates, and tiny pieces of captured food. Their primary wild food consists of grazing the surfaces of their host invertebrates without causing them harm.
In an established aquarium environment, they feed on the natural biofilm in the tank along with any leftover shrimp or fish foods, such as crushed flakes, small pellets, powdered coral foods, mysis shrimp, and frozen brine shrimp. They are surprisingly bold feeders for their size and will happily leave their host for brief moments during feeding times to grab drifting food particles.
The Sexy Shrimp (Thor amboinensis) is a very popular saltwater species that can be purchased from online retailers, local fish stores, and specialized transhippers at very reasonable, inexpensive prices.
They are frequently sold online to tropical nano-reef keeping enthusiasts as specialized additions to miniature aquariums. Current retail prices typically range from $19.99 to over $29.99 per individual.
Because these social invertebrates do best when kept in groups, many online vendors offer discounted bundle packs or bulk pricing tiers.
Although aquacultured specimens are becoming more available due to their popularity in the micro-reef hobby, the majority of Sexy Shrimp sold to tropical fish keeping enthusiasts are wild caught.
Sexy Shrimp (Thor amboinensis)
Minimum Tank Size: 5 gallons
Aquarium Type: Nano Reef or Dedicated Invertebrate Tank
Care Level: Easy to Moderate
Temperament: Peaceful
Aquarium Hardiness: Semi-Hardy (Vulnerable to sudden water shifts)
Water Conditions: 72–78°F, dKH 8 to 12, pH 8.1-8.4, sg 1.023-1.025
Max. Size: 0.75″
Color Form: Orange-Brown, White/Silver Spots, Blue Outlines
Diet: Omnivore/scavenger
Compatibility: Reef Compatible (With Caution)
Origin: Indo-Pacific, Caribbean, Western Atlantic
Family: Thoridae
Lifespan: 1 – 3 years
Aquarist Experience Level: Beginner to Intermediate
